1. Field of the Invention
The current invention relates to a work vehicle.
2. Related Art
FIG. 9 illustrates an exemplary small hydraulic excavator commonly used for public engineering works in urban areas. The small hydraulic excavator includes a counter weight 100 provided at the opposite side of a working machine 90, and a canopy 200. The counter weight 100 works for allowing the vehicle to be balanced with the load applied to the working machine. In order to ensure an operator's safety when the vehicle falls down, recent increasing demands for improved safeties require driver protection structures to conform to the strength standard specified by the ISO standards. Specifically, more canopies or cabs are required to have a Roll-over Protective Structure (ROPS).
FIG. 10 is an exploded perspective view illustrating a conventional ROPS canopy attached to a small hydraulic excavator. As shown in FIG. 10, a ROPS canopy support member 110 construct by metal sheet is attached to a frame 150 to support a canopy 210 construct by metal sheet so that the whole structure has a prescribed strength, thereby providing the ROPS canopy (refer to, for example, “Bobcat, Model 56 Hydraulic Excavator Parts Manual”, Melroe Company, November, 1986, p.A3).
Another structure is also known as shown in FIG. 11. In this structure, a counter weight 120 is provided to extend upwardly. The counter weight 120 has at the upper end side a support member 221 for supporting a canopy 220 (refer to, for example, Japanese Patent Laid-Open Publication No. 10-140607 (pp. 2–5, FIGS. 1–6).
However, the conventional ROPS canopy support member 110 as shown in FIG. 10 has a metal plate structure and thus has a problem in that the ROPS canopy support member 110 has a complicated structure having an increased weight in order to support the ROPS canopy 210 to ensure a prescribed strength, thereby requiring a significantly increased manufacture cost.
Furthermore, since an engine (not shown) is provided rearward of the ROPS canopy support member 110 shown in FIG. 10, the ROPS canopy support member 110 becomes an obstacle to the inspection or maintenance works for the engine, thus causing a problem in the maintainability of the engine.
The counter weight 120 as shown in FIG. 11 is provided to extend upwardly and thus allows the center of gravity of the counter weight 120 to move toward the rear end side, thereby to improve the stability during operations. However, since the counter weight 120 is not a structure that satisfies a prescribed strength to support a ROPS canopy, the canopy 220 cannot be an ROPS canopy.
The canopy 220 also has two support members 220a which are provided to stand at the back of an operator seat S and which have a narrow width (refer to Japanese Patent Laid-Open Publication No. 10-140607). For an operator who must frequently check the backside for an obstacle or a human, his or her rear field of vision is not always good because of the existence of the two support members 220a located around the center of his or her rear field of vision.
Japanese Laid-Open Publication No. 10-140607 also discloses in the second embodiment a case in which one thick support member 220a is provided. In this case, the support member 220a is positioned just behind the operator's seat and thus the center field of vision of the operator is blocked because the support member 220a is positioned at the center of his or her rear field of vision.
Therefore, further improvement for the operator's rear field of vision has been desired.